Hepatic Adenoma

Hepatic adenoma is a benign monoclonal hepatocellular neoplasm, mainly in women of reproductive age.

• Incidence 3 per 100,000 in oral contraceptive users, mostly women aged 20 to 45. Risk factors: oestrogen, anabolic androgen steroids, obesity, metabolic syndrome, glycogen storage disease type I and III, MODY3, Fanconi.
• Molecular subtypes:
  • HNF1A inactivated (30 to 40%): steatotic, low malignancy risk, familial MODY3.
  • Inflammatory (40 to 50%): IL6ST, STAT3 mutations, associated with obesity, high CRP, bleeding.
  • Beta catenin activated (10 to 15%): CTNNB1 mutations, high risk of malignant transformation (up to 10%), more common in men.
  • Unclassified and sonic hedgehog (bleeding risk).
• Complications: haemorrhage (10 to 25%, especially over 5 cm), rupture (life threatening), malignant transformation (4 to 8%).
• Multiple adenomatosis: 10 or more lesions.

• Asymptomatic incidental lesion in most.
• Right upper quadrant pain, palpable mass.
• Acute haemorrhage or rupture: sudden abdominal pain, hypotension, haemoperitoneum.
• Pregnancy increases growth and rupture risk.

• Ultrasound: heterogeneous mass. Contrast enhanced ultrasound, CT or MRI: arterial hyperenhancement.
• MRI with hepatobiliary contrast: HNF1A subtype shows signal drop on opposed phase (steatosis); inflammatory subtype shows atoll sign and strong T2 hyperintensity; beta catenin subtype not reliably identified.
• Biopsy for atypical lesions with immunohistochemistry (LFABP, SAA, CRP, glutamine synthetase, beta catenin).
• Alpha fetoprotein normal. Exclude hepatocellular carcinoma and focal nodular hyperplasia.
• Assess for glycogen storage disease and metabolic syndrome.

• Stop oestrogen and androgen exposure. Weight loss for obese patients. Interval imaging at 6 months.
• Women with lesions under 5 cm: observation with MRI at 6 months, then yearly. Regression in about 30 to 50% after stopping oral contraceptives.
• Indications for resection or ablation: size over 5 cm after 6 months of lifestyle change, any size in men, beta catenin activation, growing lesion, symptomatic, uncertainty on imaging, alpha fetoprotein rise, pregnancy planning with large lesion.
• Radiofrequency or microwave ablation, or transarterial embolisation, for lesions under 3 to 4 cm or unsuitable for surgery.
• Haemorrhage: haemodynamic resuscitation, urgent transarterial embolisation, then delayed resection; surgery if embolisation fails.
• Pregnancy: safe if lesion under 5 cm, ultrasound surveillance every 6 to 8 weeks; resection beforehand for larger lesions.
• Multiple adenomatosis: resect the largest lesions; liver transplant for uncontrolled disease or glycogen storage disease with malignancy.
• Follow up for 5 years after resection of beta catenin lesions.